Recently, on-line distribution of music contents employing a network, such as Internet or cable television, has come to be put to practical application.
In this distribution system for music contents, the contents distributors distributing the musical contents over the network furnish music contents over e.g., the Web. The user exploiting this music distribution system uses his or her own personal computer to access the Web furnished by the contents distributor to download the desired music contents. The user reproduces the so-acquired music contents by e.g., s player application provided within the personal computer or by e.g., a portable device connectable to the personal computer.
Meanwhile, the contents purveyor must supervise the copyright of the contents. So, the contents distributor recognizes the users, who have accessed the Web over the Internet, by the ID information or the secret identification code, to distribute the encrypted music contents only to an authorized user. The music contents are stored in a hard disc in the personal computer in a state in which they are key-managed by a secret key that cannot be freely referenced by a user. In transferring the music contents stored in the personal computer to a portable device, authorization processing is executed between a player application and a portable device before the music contents are stored on a recording medium owned by the portable device.
Meanwhile, in general, not only the music contents distributed from the network but also those from a recording medium, such as a CD, can be copied on the portable device.
However, in the conventional authentication system between the portable device and the personal computer, no distinction has been made between the player application handling only music contents copied from a recording medium, such as CD, and the player application handling music contents downloaded from the network.
So, if the authentication key between the portable device and the personal computer is broken by a person with a malignant intention, both the music contents copied from a recording medium, such as CD, and the music contents distributed over the network, are copied illicitly.
In the case of the recording medium, such as CD, in particular, charging is finished in a majority of cases at the time it is sold. However, the music contents distributed over the network are charged from time to time depending on the number of reproduction or duplication, so that more strong key management is desirable.